title: Use of shape-from-shading to estimate three-dimensional architecture in the small intestinal lumen of celiac and control patients.
abstract: BACKGROUND
  As measured from videocapsule endoscopy images, the small intestinal mucosa of untreated celiac patients has significantly greater and more varied texture compared to normal patients. Three-dimensional modeling using shape-from-shading principles may further increase classification accuracy.
  
  
  METHODS
  A sequence of 200 consecutive videocapsule images acquired at a 2s(-1) frame rate and 576×576 pixel dimension, were obtained at four locations in the small intestinal lumen of ten patients with biopsy-proven celiac disease and ten control patients. Each two-dimensional image was converted to a three-dimensional architectural approximation by considering the 256 grayscale level to be linearly representative of image depth. From the resulting three-dimensional architecture, distinct luminal protrusions, representative of the macro-architecture, were automatically identified by computer algorithm. The range and number of protrusions per image, and their width and height, were determined for celiacs versus controls and tabulated as mean±SD.
  
  
  RESULTS
  The mean number of villous protrusions per image was 402.2±15.0 in celiacs versus 420.8±24.0 in controls (p<0.001). The average protrusion width was 14.7 pixels in celiacs versus 13.9 pixels in controls (p=0.01). The mean protrusion height was 3.10±2.34 grayscale levels for celiacs versus 2.70±0.43 grayscale levels for controls (p<0.001). Thus celiac patients had significantly fewer protrusions on the luminal surface of the small intestine as compared with controls, and these protrusions had greater dimensions, suggesting they are indicative of a mosaic (cobblestone) macro-architectural pattern which is common in celiacs.
  
  
  CONCLUSIONS
  Shape-from-shading modeling is useful to explore luminal macro-architecture and to detect significant differences in luminal morphology in celiac versus normal patients, which can increase the usefulness of videocapsule studies.
authors.affiliation: Celiac Disease Center, Department of Medicine, Columbia University Medical Center, 180 Fort Washington Avenue, New York, NY 10032, USA. ciaccio@columbia.edu
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Ciaccio
authors.forename: Christina A
authors.initials: CA
authors.lastname: Tennyson
authors.forename: Govind
authors.initials: G
authors.lastname: Bhagat
authors.forename: Suzanne K
authors.initials: SK
authors.lastname: Lewis
authors.forename: Peter H R
authors.initials: PH
authors.lastname: Green
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002446:Celiac Disease / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007421:Intestine, Small / Q000473:pathology*; D008297:Male; D008875:Middle Aged
keywords: Celiac disease; Imaging; Shape-from-shading; Small intestine; Videocapsule